Memories are used within computing devices to store data. For example, data is stored and accessed within computing devices such as personal computers, notebook and laptop computers, smartphones, personal digital assistants (“PDAs”), tablet and slate devices, personal entertainment devices such as MP3 players and media players, set-top boxes, gaming consoles, appliances, embedded devices, smart meters, and other computing devices at memories such as random-access memories (“RAMs”).
Typically, data stored in RAM or other memory of a computing device is accessed by a processor and some operation is performed by the processor based on the data. For example, an encryption key can be stored at a memory and a processor can access the encryption key to encrypt or decrypt a document.
Sometimes data stored in memory does not change for literally years of operation. For example, an encryption key may be stored in the same memory locations over an extended period of time and is read many times but is never deleted or changed. When data is stored in the same memory locations over a long period of time, memory imprinting may occur due to various properties of the memory.
For example, typically, memory is comprised of a semiconductor device that stores information (or data values) based on a state (e.g., a charge value, resistance value, or some other state) of the memory cells, within the memory. Due to various properties of the memory such as manufacturing processes, types and amounts of dopants, temperature, composition, or other properties, storage of data (or data values) in the same memory locations over an extended period of time can alter the physical characteristics of the memory such that the data becomes imprinted in the memory cells. As a result of this memory imprinting, the data stored in the memory cells can be determined or read even after being deleted or over-written or after volatile memory has been powered down. In other words, the memory can be susceptible to imprinting of the data. If the memory is in a computing device that was discarded after the data was deleted from the memory, an unauthorized user may still access the data from the computing device if the data was imprinted.